JPH04267030A - Impregnated cathode structure - Google Patents

Abstract

PURPOSE:To transfer the heat from a heater to a cathode substrate via the conduction with good thermal efficiency, lower the heater temperature, and reduce power consumption by inserting and fixing a metal cup buried with a heater via alumina in advance into a sleeve supporting the impregnated cathode substrate. CONSTITUTION:Electron emitting materials BaO, CaO, Al2O3 are impregnated at the ratio 4:1:1 into porous tungsten to form a cathode substrate 1, and Os-Rh is coated on an electron emitting face. The substrate 1 is brazed to a sleeve 2 made of molybdenum with a brazing filler metal 3 made of Mo-Ru, and the back face of the electron emitting face of the substrate 1 is sealed by the brazing filler metal 3. A cylindrical heating element 10 sintered and fixed with a heater 5 by a burying agent 6 of alumina powder is inserted into a molybdenum metal cup 4 inscribed in the sleeve 2 in advance, and the outside opening end of the heating element 10 and the substrate 1 of the sleeve 2 are fixed to the opening end on the opposite side with a Ni brazing filler metal 7.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an impregnated cathode structure,
In particular, the present invention relates to an impregnated cathode assembly with reduced power consumption.

0002

[Prior Art] Conventionally, this type of impregnated cathode structure is shown in FIG.
It consists of the structure shown in . That is, a cathode substrate 31 impregnated with an electron emitting substance is soldered to one end opening of a sleeve 32 made of a high melting point metal such as molybdenum using a brazing material 33, and a heater 34 is installed inside the sleeve 32. It has a structure in which it is inserted through the opening at the other end of 32 and built-in.

0003

[Problems to be Solved by the Invention] In the conventional impregnated cathode assembly having such a structure, heat from the heater 34 disposed within the sleeve 32 is transmitted to the sleeve 32 and the cathode base 31 by radiation, so To obtain a cathode operating temperature of there were.

For example, in a cathode assembly consisting of an impregnated cathode called M type with a diameter of 2 mm and a sleeve with an outer diameter of 3 mm, the current density J = 2 A/cm2, and the cathode operating brightness temperature 1.
,000°C, the temperature of the heater 34 is approximately 1,40°C.
The heater power requires approximately 4 W at 0°C, and under this operating condition approximately 0
．． Short circuits between the lines of the heater 34 occurred at a rate of 5%.

An object of the present invention is to provide an impregnated cathode structure which has good heat efficiency from a heater, does not require large heater power, and is free from heater short-circuits and disconnections.

[0006]

[Means for Solving the Problems] The present invention provides an impregnation method comprising a cathode substrate impregnated with an electron-emitting substance, a sleeve that joins the cathode substrate to an opening at one end, and a heater inserted into the sleeve. In the cathode structure, the heater is fixed with an embedding agent in a metal cup inscribed with the sleeve, and the metal cup is inserted and fixed into the sleeve and joined to the opening at one end of the sleeve. It has a structure that heats the base by thermal conduction.

[0007]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) and 1(b) are cross-sectional views illustrating a first embodiment of the present invention.

In the first embodiment, as shown in FIGS. 1(a) and 1(b), the cathode substrate 1 is composed of porous tungsten and electron emitting substances such as BaO, CaO, and Al2O3.
The electron emitting surface is coated with approximately 5,000 angstroms of Os-Rh by impregnation at a ratio of 1:1. This cathode substrate 1 is attached to a sleeve 2 made of molybdenum.
While the cathode substrate 1 is soldered using the o-Ru brazing material 3, the back surface of the electron emitting surface of the cathode substrate 1 is sealed with the Mo-Ru brazing material 3.

[0010] Also, inside this sleeve 2, in advance,
A cylindrical heating element 10 in which a heater 5 is sintered and fixed with an alumina powder embedding agent 6 is inserted into a metal cup 4 made of molybdenum inscribed in the sleeve 2. After insertion, the outside of this cylindrical heating element 10 is inserted. The open end and the open end of the sleeve 2 on the side opposite to the cathode base 1 are fixedly supported by being brazed using Ni brazing material 7 by high frequency heating or the like.

A metal support 8 made of Mo-Re or the like connects and supports the sleeve 2 and the outer support cylinder 9, and is connected to each other by electric resistance welding.

FIG. 2 is a cross-sectional view of a second embodiment of the invention.

In the second embodiment, as shown in FIG. 2, the cathode substrate 21 is a porous metal substrate made of 20 wt% iridium and 80 wt% tungsten, and electron emitting substances such as BaO, CaO, and Al2 O3 are injected into the porous metal substrate. : Impregnated at a ratio of 1:1 and attached to a metal cup 22 made of Mo-Re,
Furthermore, the metal cup 22 has a sleeve 23 made of Mo-Re.
Laser welded. This laser welded nugget 24 consists of the outer periphery of the cathode base 21, the metal cup 22, and the sleeve 2.
It shows that laser welding is performed over 3 parts. The heater 25 is fixed in advance in a Mo-Re metal cup 26 inscribed in the sleeve 23 using an alumina embedding agent 27.

Next, the metal cup 26 in which the heater 25 is embedded in advance is inserted into the sleeve 23, and their open ends are connected and fixed by laser welding.

The method of connection to the metal support and the outer cathode support tube is the same as in the first embodiment.

The impregnated cathode structure of this example thus produced and the conventional impregnated cathode structure shown in FIG. As a result of comparative measurements of temperature and heater power, it was found that the impregnated cathode structure of this example was able to lower the heater temperature by about 300° C. on average. Furthermore, regarding the heater power, the power consumption of the heater could be reduced by about 10%. This is because the heat from the heater is transferred to the cathode substrate by radiation in the conventional type, but in the impregnated cathode structure of this example, it is transferred to the cathode substrate by conduction, so the loss from the sleeve opening is reduced. This is because heat loss from the heater legs has been reduced.

Furthermore, in the impregnated cathode assembly of this embodiment, the cylindrical heating element is manufactured as an independent component, and the sleeve holding the cathode base is assembled, attached, and fixed, making it easy to handle the components. Therefore, it is suitable for automation and has excellent mass production.

[0018] Since the process of impregnating the cathode substrate with the electron emitting material and the process of manufacturing this cylindrical heating element are independent, there is no fear that the impregnating material will adhere to the heater lead portion, and emissions from the heater lead wire will be avoided. There are no problems caused by this.

[0019]

[Effects of the Invention] As explained above, the present invention achieves efficient thermal conduction by inserting and fixing a metal cup in which a heater is embedded and fixed with alumina in advance into a sleeve that supports an impregnated cathode substrate. Since the heat from the heater can be transmitted to the cathode base, the temperature of the heater can be lowered than before and the power consumption of the heater 5 can be reduced.

Furthermore, automation is facilitated by manufacturing the cylindrical heating element in which the heater is embedded and fixed with alumina in a metal cup in an independent process, and then assembling and attaching it to the sleeve that supports the cathode base. It has the advantage of being excellent in terms of performance and mass production.

[Brief explanation of the drawing]

FIG. 1 is a sectional view illustrating a first embodiment of the present invention.

FIG. 2 is a sectional view of a second embodiment of the invention.

FIG. 3 is a cross-sectional view of an example of a conventional impregnated cathode assembly.

[Explanation of symbols]

1, 21, 31 Cathode substrate 2, 23, 32 Sleeve 3,7,33 Brazing filler metal 4, 22, 26 Metal cup 5, 25, 34 Heater 6,27 Implants 8,35 Metal support 9, 36 Outer support cylinder 10 Cylindrical heating element

Claims (1)

[Claims] 1. An impregnated cathode assembly comprising a cathode substrate impregnated with an electron emitting substance, a sleeve joining the cathode substrate to an opening at one end, and a heater inserted into the sleeve, wherein the heater is The cathode base body is fixed with an embedding agent in a metal cup inscribed with the sleeve, and the metal cup is inserted and fixed into the sleeve and joined to the opening at one end of the sleeve, and the cathode base body is heated by thermal conduction. An impregnated cathode structure characterized by having a structure.